MATLAB Answers


Why the same function is taking more time after MEX creation?

Asked by JAI PRAKASH on 27 Aug 2018
Latest activity Edited by Ryan Livingston on 29 Aug 2018
I want to create mex of 'sort()' funtion.
So I build below function
function idx = sort2(h) % h is 600x1280 'single' elements
[~,idx] = sort(h(:)); % because I just want indices only, I dont want the elements.
If I call above funtion:
Why the 'MEX' is taking more time??


Sign in to comment.




1 Answer

Answer by Ryan Livingston on 28 Aug 2018
Edited by Ryan Livingston on 29 Aug 2018
 Accepted Answer

The MATLAB Coder documentation has a section covering acclerating MATLAB code via MEX generation:
One page that's relevant to what you are seeing is:
It contains the statement:
Use MEX functions to accelerate MATLAB code only if user-generated code dominates the run time.
Avoid generating MEX functions if computationally intensive, built-in MATLAB functions dominate the run time. These functions are pre-compiled and optimized, so the MATLAB code is not accelerated significantly using a MEX function.
In MATLAB, sort is a built-in function that is hand-optimized and compiled. So the generated code likely won't be any faster and can be slower in some cases.

  1 Comment

good information
Thanks @Ryan

Sign in to comment.